Semiconductor device

ABSTRACT

A semiconductor device for forming a coil with a high inductance and a high Q value on a semiconductor substrate. A semiconductor device  10  comprises a rectangular semiconductor substrate  12 , pads formed near four corners of this semiconductor substrate  12 , pads  30  formed in the peripheral region along each side other than the corners, and a bonding wire  40  for connecting adjacent pads  20 . The circulation of the bonding wire  40  along the periphery of the semiconductor substrate  12  with the pads  20  formed in the corners constitutes a coil.

TECHNICAL FIELD

The present invention relates to a semiconductor device having a coiland an antenna formed on a semiconductor substrate.

BACKGROUND ART

There is a known semiconductor circuit wherein a spiral pattern isformed on a semiconductor substrate by using a thin film formingtechnology and this pattern is utilized as a coil.

FIG. 7 is a diagram showing a specific embodiment of the coil formed onthe semiconductor substrate. As shown in FIG. 7, a spiral coil 110 isformed with a metal pattern (thin film pattern of copper or gold forinstance) on a surface of a semiconductor substrate 100. It is possible,by forming the coil 110 on the surface of the semiconductor substrate100, to integrally form all the components such as an oscillatorincluding the coil on the semiconductor substrate 100 and eliminateexternally mounted components. It is thereby possible to reduce thenumber of components and simplify processes so as to significantlyreduce cost.

Incidentally, in the case of forming the coil 110 on the semiconductorsubstrate 100 as mentioned above, there is a problem that a highinductance cannot be secured because a diameter of the coil 110 cannotbe extended. There is also a problem that, as the semiconductorsubstrate exists immediately under the coil 110, an eddy current isgenerated on the surface of the semiconductor substrate and so a high Qvalue cannot be obtained.

DISCLOSURE OF THE INVENTION

The present invention was created in view of these points, and an objectthereof is to provide a semiconductor device capable of forming a coilhaving a high inductance and a high Q value on a semiconductorsubstrate.

To solve the above-mentioned problem, the semiconductor device accordingto the present invention comprises a first pad formed in the proximityof a corner of a rectangular semiconductor substrate and a bonding wireof which at least one end is connected to the pad. It is possible, byusing the first pad formed in the proximity of the corner of thesemiconductor substrate, to extend the bonding wire to be used as thecoil so as to obtain the high inductance. As the corner of thesemiconductor substrate is generally empty space in which no pad isformed, it is possible, by forming the first pad by using this space, toeffectively use the surface of the semiconductor substrate. The bondingwire is generally formed at a position a little distant from the surfaceof the semiconductor substrate, and so it is possible, in the case ofusing the bonding wire as the coil, to reduce an eddy current generatedon the surface of the semiconductor substrate and obtain a high Q value.

It is desirable that the above-mentioned semiconductor substrate has asecond pad to be used for internal circuit wiring in a peripheral regionexcept the corner. It is possible, by placing the above-mentioned firstpad in the corner of the semiconductor substrate and placing the secondpad for internal circuit wiring in the other peripheral region, to formthe first pad for forming the coil and the bonding wire to be connectedto the first pad without decreasing the region for forming the secondpad.

It is also desirable that the above-mentioned bonding wire is orbitallyformed to make a continuous connection between two first padscorresponding to adjacent corners. It is possible, by making an orbitalconnection between the first pads formed in the corners, to obtain ahigh inductance against limited surface area of the semiconductorsubstrate.

In the case where a plurality of first pads are formed corresponding toone corner, it is desirable that the above-mentioned bonding wire isorbitally formed to make continuous and multiple connections between thetwo first pads corresponding to the adjacent corners. It is there bypossible to form the coil of a still higher inductance.

In particular, it is desirable that the above-mentioned plurality offirst pads formed corresponding to one corner are placed in an obliquedirection against a side adjacent to this corner. It is possible, byplacing the plurality of first pads formed in one corner in the obliquedirection, to avoid mutual contact between adjacent bonding wires.

It is also desirable that the above-mentioned bonding wire is formedbetween the two first pads corresponding to the corner existing on adiagonal line of the rectangular shape. It is possible, by using thediagonally formed bonding wire, to form the coils of differentinductances compared to the case of using the bonding wire formed alonga periphery.

It is also desirable that the bonding wire connected to theabove-mentioned first pad is formed after finishing formation of theother bonding wire to be connected to the second pad. It is therebypossible to form the coil just by lastly adding a process of forming thebonding wire corresponding-to the first pads so as to minimize changesin the processes.

It is also desirable that the coil for the antenna is formed by usingthe bonding wire connected to the above-mentioned first pad and thiscoil for the antenna is connected to a circuit formed on thesemiconductor substrate. Thus, it is possible to form the coil for theantenna and the entire circuit connected thereto on the semiconductorsubstrate so as to reduce the component cost, manufacturing cost and soon by decreasing the number of components compared to the case of usingthe antenna as an externally mounted component.

It is also desirable that the coil for the inductor is formed by usingthe bonding wire connected to the above-mentioned first pad and thiscoil for the inductor is connected to the circuit formed on thesemiconductor substrate. Thus, it is possible to form the coil for theinductor and the entire circuit connected thereto on the semiconductorsubstrate so as to reduce the component cost, manufacturing cost and soon by decreasing the number of components compared to the case of usingthe coil for the inductor as the externally mounted component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the semiconductor device according to thisembodiment;

FIG. 2 is a partial perspective view of the semiconductor device shownin FIG. 1;

FIG. 3 is a diagram showing order of forming the bonding wires on thesemiconductor device;

FIG. 4 is a plan view showing a semiconductor device on which thebonding wire is set to make a round twice;

FIG. 5 is an overview plan view showing a semiconductor device havingthe coil making a connection between the two pads existing on thediagonal line of the semiconductor substrate via the bonding wire;

FIG. 6 is a plan view showing an overview configuration of asemiconductor device having two types of coils formed on thesemiconductor substrate; and

FIG. 7 is a diagram showing a specific embodiment of the coil formed onthe semiconductor substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, a semiconductor device according to an embodiment of thepresent invention will be described in detail by referring to thedrawings.

FIG. 1 is a plan view showing the semiconductor device according to thisembodiment. And FIG. 2 is a partial perspective view of thesemiconductor device shown in FIG. 1. As shown in these drawings, asemiconductor device 10 according to this embodiment is comprised of arectangular semiconductor substrate 12, a plurality of pads 20 formed inthe proximity of four corners of the rectangular semiconductor substrate12, a plurality of pads 30 formed in a peripheral region along each sideother than the corners, and bonding wires 40 for making connectionsbetween adjacent pads 20.

The bonding wires 40 make continuous connections between the two pads 20formed at the adjacent corners. To be more precise, a pad 20 a is formedon one corner and a pad 20 b is formed in the corner adjacent to thiscorner respectively, and a bonding wire 40 a is formed to make aconnection between the two pads 20 a and 20 b. Also, a pad 20 c isformed in the corner adjacent to the corner on which a pad 20 b isformed, and a bonding wire 40 b is formed to make a connection betweenthe two pads 20 b and 20 c. Likewise, a pad 20 d is formed in the corneradjacent to the corner on which the pad 20 c is formed, and a bondingwire 40 c is formed to make a connection between the two pads 20 c and20 d. Furthermore, a pad 32 is formed between the pad 20 a and 20 d andin the proximity of the pad 20 a, and a bonding wire 40 d is formed tomake a connection between the pads 20 d and 32. Thus, one ends of thebonding wires 40 a and 40 d are terminated by the pads 20 a and 32, andeach of the bonding wires 40 a, 40 b, 40 c and 40 d is relayed by thepads 20 b, 20 c and 20 d so that the coil almost making a round alongthe periphery of the semiconductor substrate 12 as a whole is formed.

FIG. 3 is a diagram showing order of forming the bonding wires on thesemiconductor device 10 of this embodiment. If the semiconductor device10 of this embodiment is fixed at a predetermined position on a printedcircuit board (not shown), wiring for the pad 30 formed in theperipheral region except the corner is performed first by wire bondingusing a bonding wire 50 as shown in FIG. 3. This process is the same asthe wire bonding process performed in the past. Next, as shown in FIGS.1 and 2, the wiring is performed by the wire bonding for making aconnection between the pads 20 or between the pads 20 and 32 provided onor in the proximity of the corner. The bonding wires 40 formed in thiscase are formed to jump over the space between the adjacent pads 20 orbetween the pads 20 and 32 so as to maintain a state of being clear ofthe pad 30 formed underneath them and the bonding wire 50 connected tothe pad 30.

Incidentally, the coil formed by the above-mentioned bonding wire 40 maybe used as the coil for an antenna. Thus, it is possible to form thecoil for the antenna and a transmitting circuit, a receiving circuit andso on connected thereto as a whole on the semiconductor substrate 12 soas to reduce the component cost and manufacturing cost by decreasing thenumber of components compared to the case of using the antenna as anexternally mounted component.

Otherwise, the coil formed by the above-mentioned bonding wire 40 may beused as the coil for an inductor. Thus, it is possible to form the coilfor the inductor and an oscillator, a tuning circuit and so on connectedthereto as a whole on the semiconductor substrate 12 so as to reduce thecomponent cost and manufacturing cost by decreasing the number ofcomponents compared to the case of using a coil antenna for the inductoras an externally mounted component.

Thus, as the bonding wire 40 to be used as the coil is formed by usingthe pads 20 formed in the proximity of the four corners of thesemiconductor substrate 12, it is possible to extend length of thebonding wire 40 against limited surface area of the semiconductorsubstrate 12 so as to obtain a high inductance.

As the corner of the semiconductor substrate 12 is generally empty spacein which the pad 30 used for internal circuit wiring is not formed, itis possible, by forming the pad 20 to be used for forming the bondingwire 40 to be used as the coil by using this space, to effectively usethe surface of the semiconductor substrate 12.

Furthermore, the bonding wire 40 is formed at a position a littledistant from the surface of the semiconductor substrate 12, and so it ispossible, in the case of using the bonding wire 40 as the coil, toreduce an eddy current generated on the surface of the semiconductorsubstrate 12 and obtain a high Q value.

The present invention is not limited to the above embodiment, butvarious modified embodiments are possible within the gist thereof. Forinstance, according to the above-mentioned embodiment, the bonding wire40 is formed to almost make a round along the periphery of thesemiconductor substrate 12. However, it may also be set to make a roundless than once or twice or more.

FIG. 4 is a plan view showing a semiconductor device 10A on which thebonding wire 40 is set to make a round twice. As shown in FIG. 4, thepads 20, 24 and 32 are formed in the proximity of one corner of thesemiconductor substrate 12. One of the two pads 20 and 32 iscorresponding to the start of winding of the coil and the other iscorresponding to the end thereof. The pad 24 has the bonding wire 40constituting a peripheral coil connected to a bonding wire 42constituting an inner coil, and makes a trunk connection between thesecoils.

The pads 20 and 22 are formed in the proximity of the other corners. Thetwo pads 20 and 22 are placed in an oblique direction against a sideadjacent to a corresponding corner. The pad 20 on one hand has twobonding wires 40 constituting the peripheral coil connected thereto, andrelays them. The pad 22 on the other hand has two bonding wires 42constituting the inner coil connected thereto, and relays them.

Thus, it becomes possible, by setting the bonding wire to make a roundtwice or more, to form the coil having a high inductance. As shown inFIG. 4, it is also possible, by placing the pads 20 and 22 in theoblique direction in the proximity of the corners, to prevent theperipheral coil and inner coil formed by relaying the pads 20 and 22from overlapping so as to avoid mutual contact between the bonding wire40 and the bonding wire 42.

According to the above-mentioned embodiment, the bonding wire 40 isformed along the periphery of the semiconductor substrate 12. However,it is also feasible to connect the pads 20 formed on the cornersexisting on a diagonal line of the rectangular semiconductor substrate12 with the bonding wire.

FIG. 5 is an overview plan view showing a semiconductor device 10Bhaving the coil making a connection between the two pads 20 existing onthe diagonal line of the semiconductor substrate 12 via the bonding wire40B. As shown in FIG. 5, it is possible, by using the bonding wireformed along the diagonal line or combining this bonding wire with thebonding wire 40 shown in FIG. 1, to form the coil having an inductancedifferent from that in the case of merely having the bonding wire 40make a round along the periphery of the semiconductor substrate 12 so asto use it properly as required.

The above-mentioned embodiment described the case of forming one coil onthe semiconductor substrate 12. However, it is also feasible to sectionthe surface of the semiconductor substrate 12 so as to form two or moretypes of coils.

FIG. 6 is a plan view showing an overview configuration of asemiconductor device 10C having two types of coils formed on thesemiconductor substrate 12. As shown in FIG. 6, it is possible, byassuming the case of dividing the surface of the semiconductor substrate12 into two regions and separately forming the bonding wires along theperiphery of the divided regions, to form the two types of coils. As forthe thinkable cases of usage of these coils, one may be used as the coilfor the antenna and the other as the coil for the inductor, or one maybe used as the coil for the antenna for transmission and the other asthe coil for the antenna for reception, for instance.

INDUSTRIAL APPLICABILITY

As described in detail above, according to the present invention, it ispossible, by using the first pad formed in the proximity of the cornerof the semiconductor substrate, to extend the bonding wire to be used asthe coil so as to obtain the high inductance. As the corner of thesemiconductor substrate is generally empty space in which no pad isformed, it is possible, by forming the first pad by using this space, toeffectively use the surface of the semiconductor substrate. The bondingwire is generally formed at a position a little distant from the surfaceof the semiconductor substrate, and so it is possible, in the case ofusing the bonding wire as the coil, to reduce the eddy current generatedon the surface of the semiconductor substrate and obtain a high Q value.

1. A semiconductor device comprising a first pad formed in the proximityof a corner of a rectangular semiconductor substrate and a bonding wireof which at least one end is connected to said first pad, characterizedin that said semiconductor substrate has a second pad to be used forinternal circuit wiring in a peripheral region except said corner. 2.The semiconductor device according to claim 1, characterized in thatsaid bonding wire to be connected to said first pad is formed afterfinishing formation of the other bonding wire to be connected to saidsecond pad.
 3. A semiconductor device comprising a first pad formed inthe proximity of a corner of a rectangular semiconductor substrate and abonding wire of which at least one end is connected to said first pad,further comprising a second pad, characterized in that said bonding wireis orbitally formed to make a continuous connection between said firstand said second pad corresponding to adjacent corners.
 4. Asemiconductor device comprising a first pad formed in the proximity of acorner of a rectangular semiconductor substrate and a bonding wire ofwhich at least one end is connected to said first pad, characterized inthat a plurality of said first pads are formed corresponding to said onecorner, and said bonding wire is orbitally formed to make continuous andmultiple connections between ones of said first pads.
 5. Thesemiconductor device according to claim 4, characterized in that saidplurality of first pads formed corresponding to said one corner areplaced in an oblique direction against a side adjacent to this corner.6. A semiconductor device comprising a first pad formed in the proximityof a corner of a rectangular semiconductor substrate and a bonding wireof which at least one end is connected to said first pad, furthercomprising a second pad, characterized in that said bonding wire isformed between said first and said second pads corresponding to cornersexisting on a diagonal line of said rectangular shape.
 7. Asemiconductor device comprising a first pad formed in the proximity of acorner of a rectangular semiconductor substrate and a bonding wire ofwhich at least one end is connected to said first pad, characterized inthat a coil for an antenna is formed by using said bonding wireconnected to said first pad and this coil is connected to a circuitformed on said semiconductor substrate.
 8. A semiconductor devicecomprising a first pad formed in the proximity of a corner of arectangular semiconductor substrate and a bonding wire of which at leastone end is connected to said first pad, characterized in that a coil foran inductor is formed by using said bonding wire connected to said firstpad and this coil is connected to a circuit formed on said semiconductorsubstrate.